This section is intended to introduce the reader to various aspects of art which may be related to various aspects of the present invention which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
With the advent of standardized architectures and operating systems, computers have become virtually indispensable for a wide variety of uses from business applications to home computing. Whether a computer system is a personal computer or a network of computers connected via a server interface, computers today rely on processors, associated chipsets, and memory chips to perform most of the processing functions, including the processing of system requests. The more complex the system architecture, the more difficult it becomes to process requests in the system efficiently. Despite the increase in complexity of system architectures, demands for improved processing speed continue to drive system design.
Some systems include multiple processor units or microprocessors connected via a processor bus. To coordinate the exchange of information among the processors, a host/data controller is generally provided. The host/data controller may be further tasked with coordinating the exchange of information between a plurality of processors and the system memory. The host/data controller may be responsible not only for the exchange of information in the typical Read Only Memory (ROM) and the Random Access Memory (RAM) but also the cache memory in high speed systems. Cache memory is a special high-speed storage mechanism which may be provided as a reserved section of the main memory or as an independent high speed storage device. The cache memory may be a portion of the RAM that is made of high speed static RAM (SRAM) rather than the slower and cheaper dynamic RAM (DRAM) which may be used for the remainder of the main memory. Alternatively, cache memory may be located in each processor. By storing frequently accessed data and instructions in the cache memory, the system may minimize its access to the slower main memory and thereby may increase the request processing speed in the system.
The host/data controller may be responsible for coordinating the exchange of information among several buses, as well. For example, the host controller may be responsible for coordinating the exchange of information from input/output (I/O) devices via an I/O bus. Further, systems may implement split processor buses wherein the host controller is tasked with exchanging information between the I/O bus and a plurality of processor buses. Due to the complexities of the ever-expanding system architectures which are being introduced in today's computer systems, the task of coordinating the exchange of information becomes increasingly difficult. Because of the increased complexity in the design of the host controller due to the increased complexity of the system architecture, more cycle latency may be disadvantageously injected into cycle time for processing system requests among the I/O devices, processing units, and memory devices which make up the system.